Final answer:
The Old Minnehaha County Jail is described by a term suggesting it features an 'architectural mashup,' indicating a mix of styles rather than a singular architectural style.
Step-by-step explanation:
The architectural style used on the Old Minnehaha County Jail is not explicitly mentioned in the reference provided. Architectural mashup suggests that the jail might combine elements from various styles rather than adhering to a single recognized architectural genre. This could involve elements found in buildings constructed in the Post-War era or even incorporating multiple periods or stiles reflecting the wide range of influences from different times and cultures, as seen in Spanish religious architecture.